Therapeutic lamp



F. A. ANDERSON THERAPEUTIC LAMP Filed Jan. 6, 1928 Sept. 24, 1929.

Patented Sept. 24, 1929 UNITED STATES PATENT OFFICE FRITZ A. ANDERSON, OF MILTON, WISCONSIN, ASSIGNOR TO THE BURDICK OORPORA lION, OF MILTON, WISCONSIN, A CORPORATION OF DELAWARE THERAPEUTIC LAMP Application filed January 6, 1928. Serial No. 244,818.

My invention relates to therapeutic lamps. It will be explained as embodied in a watercooled lamp of the mercury-arc-tube type particularly adapted for ultra-violet ray therapy.

.The lamp herein illustrated and described is an improvement upon the lamp set forth in my Patent No. 1,680,583 granted August 14, 1928.

The lamp set forth in my aforesaid patent completely eliminated the objectionable lens fogging that had been a source of trouble in prior lamps wherein the circulating coolingwater came into contact with the lens faces." It was found, however, that a solid quartz lens of the thickness required absorbed or screened out some of the shorter ultraviolet rays and that some of the longer heat and infra-red rays passed therethrough. Thus the ultra-violet emanations were decreased and the radiant heat was somewhat greater than desired. Although this difliculty was overcome by using a hollow lens filled with distilled water and with relatively thin quartz walls yet, with the present day facilities for producing and working fused quartz, it was found that the proper fitting of the lens to provide a seal against the circulating coolingwater rendered the construction somewhat expensive.

One of the objects of my present invention is to overcome the aforementioned objections.

Another object is to provide a lamp that will eliminate fogging of the lenses and will screen out the longer infra-red rays but not the shorter ultra-violet rays, and that canbe inexpensively manufactured.

Another object is to provide a lamp particularly suited for direct contact with the pa tients body.

Another object is to safe and reliable.

' Other objects and advantages will hereinafter appear.

One embodiment of the invention, in corporated in a lamp of a generally well known type similar to that disclosed in F. A. Anderson Patent No. 1,435,198 dated November 14, 1922, is illustrated in the accompanying drawing wherein,

provide a lamp that is Fig. 1 is a substantially axial vertical section through a complete therapeutic lamp embodying my invention;

Fig. 2' is a partial front elevation of the lamp; and

Fig. 3 is a perspective of the lens, partly in section to illustrate more clearly the construction and method of its production.

The lamp chosen for illustration com prises, in general, a double-walled housing and a mercury-arc-lamp-tube or burner 5 of the well known type set forth in the aforesaid Anderson patent. The double-walled housing includes an inner casing 6 and an outer casing 7 spaced apart to provide there between a chamber through which a cooling-fluid may be circulated to maintain the desired temperature. This cooling-fluid chamber is closed at its upper end by a top wall 8 and at its lower end by a bottom wall 9. Water is fed to this chamber through an inlet connection 10 and is removed through an outlet connection 11. The inlet and outlet cooling-water connections may be coupled respectivelyto a suitable source of water supply and to waste. Electrical'connections to the arc burner terminals are completed through conductors 12 and 13 leading from a receptacle 14 and a plugconnector 15. The construction thus far described is well known and is illustrated and described in detail in the aforesaid Anderson patent.

The inner casing is provided with an opening or light window, preferably circular in shape, surrounded by an outwardly projecting annular flange 16 which is internally threaded at .its forward edge. The outer casing is provided with a similar opening or light window surrounded by an annular flange 17. These two windows are in alignment so that the rays from the lamp tube or burner can passtherethrough from the inside of the housing to the outside thereof. The lens, to be hereinafter described in detail, is held by an annular two part holder or support consisting of a rear section 18 and a forward section 19. Holdersection 18 has a relatively heavy inwardly projecting annular flange 20,. which is externally threaded to fit the threads of Window flange 16, and at its forward end is externally threaded to fit the internally threaded end of holder section 19. Section 19 has an annular recess for fitting over window flange 17 and thereby clamp the lens holder to the outer casing. Solder or other suitable packing may be used to insure a water tight seal at the joints between the lens holder and the inner and outer casings so that the'coolingwater cannot escape or enter the burner chamber.

Rear lens holder section 18 is provided with a series of water inlet holes 21 and outlet holes 22 communicating with the coolingwater chamber of the housing and through which the cooling-water may circulate into and out of an annular space 23 about the lens, as will be hereinafter explained.

The lens, designated generally by the numeral 25, and preferably of cylindrical shape, is seated at its rear edge in an annular ledge 26 in holder section flange 20 and at the front edge within an annular flange 27 of front holder section 19. Packing rings 28 and 29 of asbestos composition or other suitable material may be interposed between the rear and frontedges of the lens respectively to insure water tight joints. The lens holder is held in place by an adapter ring 30 of an applicator adapter such as described in FJA, Anderson Patent No. 1,559,062 dated October 27, 1925, which is internally. threaded to fit external threads on the forward end of front lens holder section 19. When ring 30 is screwed tightly into place the packing rings insure the proper seating of the lens and water tight joints; and yet the adapter ring can be removed to replace a lens if desired.

In order that the lamp may be used for direct application to the patient without the intervention of any special applicators (a technique sometimes desired) a plane window or lens 31 (preferably of rock quartz) is used to close the opening in adapter ring 30. Thus the front rim face of ring 30 is provided with a rearwardly diverging annuar groove 32 which receives the similarly bevelled rim of window 31. I prefer to leave a considerable clearance between groove 32 and lens 31 and to fill this clearance space with relatively low temperature melting solder or-other metal. The solder will hold the window 31 in place flush with the frontface of adapter ring 30 without undue strain, and effect a dust proof seal.

The lens, which is illustrated in detail in Figs. 1 and 3, comprises a distilled water filled cell of fused quartz and a surrounding sleeve or ferrule of metal. The quartz cell of the lens comprises a tubular fused quartz body 35 having the opposite ends thereof closed by fused quartz windows 36. lVindows 36 are set into body 35 flush with the respective ends thereof and fused in place so as to form a water tight drum. Prior to the placement of windows 36 the tubular body of the lens is provided with a small opening into which a short length of quartz tubing is fused through which air may be exhausted from the lens chamber and the same filled with a suitable fluid such as distilled water. After the end windows are sealed in place the chamber of the lens is exhausted by a suitable vacuum pump and then filled with distilled water taken directly from the still so as to afford no opportunity for air absorption or entrainment. When the cell is filled the tube heretofore mentioned is cut off and sealed by fusion in the usual way, leaving a slight projecting bulge 37 which will act as a small expansion chamber when the lens is heated in service. Around the fused quartz water filled cell thus produced a metal sleeve or ferrule 38 is cast. Preferably the opposite edges of this metal sleeve project slightly beyond the surfaces of the adjacent lens windows 36. The metal I prefer to use for this external sleeve is sufliciently soft to permit ready machining to fit the annular seats provided in holder flanges 20 and 27 and sufliciently ductile to permit a water tight seal to be there made without gaskets; the melting point should be sufiiciently low so that the sleeve or ferrule will act as a safety valve in case the water within the cell should become hot enough to boil and so that the metal can be cast around the quartz cell when the same is filled with water. Also the coefficient of expansion of the metal should be low enough so as not to i1npose .injurious strains upon the quarts cell when the metal sets. It has been found that woods metal satisfactorily meets the foregoing requirements. This metal is an alloy of tin, lead, bismuth and cadmium, having a melting point at approximately 158 F.

The lens thus formed may have its outer metallic sleeve or sheath very easily and inexpensively machined to fit the seats provided therefor in the lens holder and, when securely seated by the adapter ring, as hereinbefore described, provides water tight joints for preventing leakage of the cooling-water circulating thereabout so that none of the cooling-water can come into contact with either face of the lens although the water circulates freely about the edge of the lens to cool the same.

In operation cooling water enters the chamber between the inner and outer casings of the lamp housing through inlet 10, passes up through openings 21, circulates about the edge of lens 25 and out through openings 21, leaving the chamber by way of outlet 11. Thus the circulating cooling water does not come into contact with any lens face but only with the edge thereof. Satisfactory cooling of the lens is thus attained without danger of fog ging from the content of the circulating coolscreening out infrared rays.

of the lens reduces the amount of ultra-violet ray screening, while the distilled water in the lens cell cools the radient emanations by It has been found that passing the rays through about one inch of distilled water will screen out the infra-red rays longer than about 1400 mu. which will provide radiations that are cooler than those from lamps using a thin film of circulating water in the path of the rays. Since this small amount of water is always confined and sealed within the quartz cell and may be purified before being used, it will not fog the lens. The metal sheath or sleeve used in the, construction of the lens makes a stronger lens, relieves the quartz from strains and, being soft and easily machined is readily fitted and tightly sealed in place. Furthermore, when metal having a melting point below the temperature of boiling water is used the sleeve will give way before the water boils and creates to high pressure within the lens cell. Thus the danger of exploding lenses is reduced. The forward flush quart-z window may serve as a direct compression applicator against the patient, because, being spaced from the inner lens and being affected by the circulating cooling water, it will remain relatively cool.

Having thus illustrated. and described one embodiment of my invention, what I claim and desire to secure by United States Letters Patent is as follows:

1. A therapeutic lamp housing comprising a double walled casing for enclosing a. lamp and having a window t-herethrough for the passage of rays generated by the lamp, and a hollow-quartz fluid-filled lens for closing the window in the casing and bridging the space between the casing walls so that a cooling medium circulating between the walls flows about the edge only of the lens.

2. A therapeutic lamp housing comprising a double walled casingfor enclosing a lamp, said walls having aligned window openings for the passage of rays from the lamp and the space therebetween constituting a cooling-fluid circulating chamber; and a lens for closing the window openings and bridging the space between the casing walls,

said lens consisting of a water filled quartz.

cell, and a metallic sleeve about the periphery thereof and in the path of the circulating cooling-fluid.

3. A therapeutic lamp housing comprising an outer casing and an inner casing spaced apart to provide a cooling-fluid circulating chamber therebetween and having aligned windows for the passage of light rays from a lamp within the housing, connections for circulating a cooling-fluid through said chamber, a lens holder comprising a ring attached to the inner casing and a ring attached to the outer casing, said rings cooperating to hold a lens therebetween and form a cooling-fluid space about the edge only of the lens and in communication with said chamber, and a lens seated and retained by the lens holder.

4. therapeutic lamp housing comprising a casing having double walls with a water circulating chamber therebetween, said \valls having aligned window openings for the passage of rays from a lamp mounted within the housing, a lens for closing the window openings in the casing and lying in the path of the water circulating through said chamber, an adapter ring on the outer casing about the window opening therein for the attachment of applicators used to conduct light from the lamp, and a window lens mounted in the adapter ring flush with the front face thereof and out of contact with the circulating water. C

5. A therapeutic lamp housing having inner and outer spaced apart casings with a cooling-water circulating chamber, therebctween and aligned window openings, connections for circulating cooling-water through .said chamber, a water cooled lens for closing said window openings and presenting its edge only to the circulating cooling-water, a ring mounted on the outer casing about the window opening therein, and a window lens mounted in the ring flush with the front face thereof and out of contact with the water cooled lens and the circulating cooling-water.

6. A therapeutic lamp housing having inner and outer spaced apart casings with aligned window openings therein and a cooling-water circulating chamber therebetween; a lens; and a lens holder comprising a ring secured to the inner casing for supporting one end of the lens, and a separate ring secured to the first mentioned ring for sup porting the other end of the lens, said rings providing a cooling-water circulating space about the lens in communication with said cooling water chamber.

7. A therapeutic lamp lens comprising a hollow fused quartz cell, and a sleeve of metal cast about the periphery thereof.

8. A therapeutic lamp. lens comprising a cylindrical closed cell of fused quartz, and

a sleeve of ductile low melting point metal east about the periphery thereof.

9. A therapeutic lamplens comprising a substantially drum shaped closed cell of' fused quartz filled with distilled water, and a sleeve of ductile metal having a melting point below the boiling point of water cast about the periphery thereof.

10. A lens for a water-cooled therapeutic lamp housing comprising a relatively thin walled sealed cell of fused quartz filled with a liquid, and a sleeve of metal cast about the periphery of the quartz cell, said metal be- V ing relatively ductile, having a melting point below the boiling point of the liquid in the cell and having a relatively low coefficient of expansion.

In Witness whereof, I hereunto subscribe my name this 3rd day of January, 1928.

FRITZ A. ANDERSON. 

